Volumetric diaphragm pumps for gasoline injection



Aug. 25, 1959 L, RA 2,900,916

VOLUMETRIC DIAPHRAGM PUMPS FOR GASOLINE INJECTION Filed Oct. 11, 1955 2Sheets-Sheet l FIG.2. 1

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INVENTOR. LUCIEN PERAS A TTORNEY Aug. 25, 1959 L. PERAS 2,900,916

VOLUMETRIC DIAPHRAGM PUMPS FOR GASOLINE INJECTION Filed Oct. 11, 1955 2Sheets-Sheet 2 0 BY LUCIEN PERA FIG. 30. I, W

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United States Patent VOLUMETRIC DIAPHRAGM PUMPS FOR GASOLINE INJECTIONLucien Pras, Billancourt, France, assignor to Regie Nationale des UsinesRenault, Billancourt, France Application October 11, 1955, Serial No.539,897 Claims priority, application France October 14, 1954 1 Claim.(Cl. 103-38) The invention relates to an improvement to volumetric pumpswherein the delivery of the fluid is effected by the successiveactuation of a certain number of pressure members resting against aflexible wall.

It is the object of this improvement to render the operation thereofmore reliable and less sensitive to variations in temperature, toincrease its robustness, its simplicity of manufacture and itssimplicity of use.

.The known pumps having a deformable chamber are based on the followingprinciple: a chamber, which may be circular for example, is formed by aplane surface or face into which lead suction and delivery pipes, saidface being covered with a flexible wall or diaphragm. Pressure members,which are actuated successively in such a manner as to exert pressureson the deformable diaphragm, are situated around the circumference ofthe diaphragm. The variations in volume of the chamber between thediaphragm and the face eifect the suction and delivery of the fluid.

According to a known method of constructing these pumps, the action ofthe pressure members is not exerted vertically in relation to thediaphragm, but with a rocking movement. The pressure members arearranged in a circle, and their outward-facing ends are seated in such amanner that their rocking movements can take place about a fulcrumsituated in the seating. The opposite ends of the pressure members allrest on a movable circular member, the distance of which from thediaphragm can be regulated in the pump shaft. It will readily beunderstood that any regulation of the distance of the moving member inrelation to the face will cause variation in the volume of fluid drawnin and delivered for each alternating movement effected by a pressuremember.

The delivery is obtained by the successive application of the pressuremembers to the diaphragm by means of a set of rollers which roll oversaid pressure members.

One feature of the present invention is to replace the set of rollers,the axis of which is generally parallel to the plane of the pressuremembers, by a single rolling bearing, the axis of which forms arelatively large angle with the plane of the pressure members, thesurface of said rolling bearing resting on the pressure members beingchamfered, and the apex of a cone drawn through the chamfered surfaceslying in the centre of the circle of the pressure members in such amanner that said chamfered surface rolls, without sliding, over the saidplane.

A further feature of the invention consists in mounting the aforesaidmovable delivery-regulating support in such a manner that the onlyspring behind the actual body of the pump is the one the flexibility ofwhich determines the position of said support, and in shifting themember sensitive to the regulating parameter to the other end of thepump by extending the stern of the support through the driving shaft ofthe rolling bearing, said parameter being the negative pressureobtaining in the engine manifold in the event of use as apetrol-injection pump.

A gasoline injection pump according to the invention, for a 4-cylinderengine, will now be described by way of non-limiting example, withreference to the accompanying drawings.

Figure 1 is a section showing the principle of the known diaphragm pump;

Figure 2 shows a longitudinal section through the pump according to theinvention; a

Figure 3 shows a section in plan along AA;

Figure 3a is a detail section along III-III;

Figure 4 is an end view showing the position of the limiting spring.

Referring to the drawing, Figure 1 illustrates diagrammatically theprinciple of this pump: a flexible diaphragm 1 is mounted between a face2 and an annular member 3 surrounding a central member 4. Pressuremembers 5 are arranged radially between the annular member 3 and asupport 7, the distance of which from the face is variable; by means ofa roller, not illustrated, the pressure members are successively appliedagainst the face in such a manner as to cause suction and deliveryeifects between the face and the diaphragm, said space being suitablyconnected to gasoline inlet and delivery pipes.

Referring to the device illustrated in Figures 2 and 3, it will be seenthat the pump body 2 is provided with four inlet pipes such as 11 andfour delivery outlets such as 12. The diaphragm 1 is applied against itsface, in known manner, by an external ring 14 and bolts 15. Washers 16enable the diaphragm to be given a welldefined, limited tightness. Thering 14, as well as the sleeve 17 and the nut 18, likewise grip againstthe diaphragm a plate 4 in the form of a four-armed star leaving fouropenings in each of which is a set of two pressure members 5, which aresubstantially trapezoidal in shape and of the same thickness as theplate.

In Figures 1 and 2, the plane AA is the outer plane of the pressuremembers when they are applied against the diaphragm.

The outer supports for the pressure members consist of the members 3.There are four supports such as 3, one for each set of pressure members.They are fixed in such a manner that the various pivoting motions of thesets of two pressure members can be selected separately. All thepressure members bear on the movable support 7 in the centre. It is theposition of this support which regulates, in known manner, the liftingof the pressure members and hence the delivery. This support has anextension 19 mounted for sliding in a sleeve 17 and the end of whichreceives the thrust of the leaf spring 20. This leaf spring is supportedat its two ends on adjustable supports such as 21, screwed into the body2.

The shaft of the movable support 7 is continued on the other side by astem 22, the mounting of the. other end of which will be describedlater. This stem 22 passes through the main shaft 23 of the pump. Thisshaft is mounted in a conventional manner between two taper rollerbearings 24 in a housing 25, fixed to the engine at 52. The pump bodyassembly, and particularly the ring 14, is fixed concentrically on thishousing 25 by the bolts 26. The shaft 23 has a seating 27 which is notparallel with the axis of the shaft 23 and on which a ball bearing 28 ismounted with a tight fit. The inner ring of this ball bearing isrelieved at 29 to avoid contact with the support 7. Its outer ring ischamfered at 30 and the apex of a cone drawn through the chamferedsurface is at the point 0 which is in the plane AA, the centre of thepump-body assembly; nat

urally, the axis of the cone is also the axis of the seating 27.Movement is imparted to said shaft 23 by a helical pinion 31 which isdriven by a perpendicular pinion 32.

At the other end of the housing 25 is a casing 35 which is fixed on theone hand to the housing 25 and which receives in the centre animpervious diaphragm 36 through which passes the end of the stem 22,sealing being eflected by gripping the diaphragm between two washers 37by means of the nut 38.

A main metering diaphragm 39 separates the casing 35 from an outercasing 40. This diaphragm has in the centre an inner plate 41 whichrests against the end 23 of the stem 22 and an outer plate 42 of thesame diameter. These two plates are pressed together through thediaphragm by means of bolts 44. These bolts serve to centre a highlyflexible spring 51. This spring 51 therefore urges the assembly of theplates 4142 against the stem 22 in opposition to the regulating spring20 at the other end of the pump.

The outer casing 40 is generally brought into communication with theatmosphere through the central conduit 49, but provision is made for thepossibility of this pipe 49 being brought into communication with theneck of a venturi situated in the inlet manifold for the engine fuelmixture to which the present pump is applied, upstream of theair-regulating throttle. On the other hand, the casing 35, which isentirely enclosed on all sides, either by fixed walls or by diaphragms,is brought into communication through the pipe 50 with the inletmanifold of the engine, downstream of the throttle, that is to say in azone where there is absolute pressure on the engine valves.

The pump may equally well be mounted horizontal 1y or vertically.

The spring 20 is a leaf spring of simple shape, the flexibility of whichmay be determined simply by its thickness.

Operation is as follows:

When the pump is mounted, the spring 51 urges the plates 41 and 42against the stem 22 of the movable support in such a manner that saidsupport 7 aligns the pressure members in the plane AA; the leaf-spring20, regulated by the supports 21, is put under tension in such a mannerthat it first compensates the effort of the spring 51, then permits thesupport 7 to be raised by a suitable amount to obtain the gasolinedelivery corresponding to the full load on the engine. The pump isconnected up in the following manner: the pipes 11 are in communicationwith a conventional feed pump which supplies a delivery pressure of theorder of one atmosphere. The delivery pipes 12 are brought intocommunication with the engine injectors. The pipe 50 is connected to theinlet manifold down-stream of the throttle; the pipe 49 may be connectedeither to a venturi, or directly to the inlet manifold upstream of thethrottle.

As soon as the engine is started, a negative pressure is formed in themanifold downstream of the throttle. This negative pressure is exertedinside the casing 35 and particularly on the surface of the diaphragm 39and of the plate 41. A considerable effort is therefore added to theeffort of the spring 51 and increases the flexion of the spring 20,which determines a new position for the support 7 causing a reduced liftof the pressure members, thus preparing for the gasoline delivery to beless than the delivery at full load.

The feed pump, which begins to operate, delivers gasoline under thediaphragm at 11, under the aforesaid slight pressure, thus moving thepressure members until they come into contact with the support 7.

The rotational movement of the engine is transmitted by means of thepinions 32 and 31 to the shaft 23 and the bearing 28 begins to rotate onthe plane AA,

When the corresponding generating line of the cone 30 passes over a setof pressure members, the first pressure member begins by cutting thecommunication with the inlet pipe and the second pressure member drivesthe gasoline into the pipe 12 under the pressure determined by thesetting of the injector. When the accelerator is depressed and thethrottle opens progressively, the negative pressure in the pipe 50diminishes, the force which was added to the spring 51 diminisheslikewise, and the spring 20 restores the support 7 to a position whichallows the pressure member greater clearance; when the throttle is fullyopen, there is no longer any elfort added to the spring 51 and thesupport 7 resumes the initial position corresponding to delivery underfull load. When the engine is not only under full load but also at fullspeed, that is to say when it is developing the whole of its power, thespeed of the air in the inlet pipe causes a slight negative pressure inthe pipe 49, and hence a slight effort which opposes the spring 51,tending to raise still further the support 7 and to increase slightlythe delivery at full load.

It will be noted that the mounting of the bearing 28 instead of the pumprollers is an improvement on the known arrangement, considerably reducesthe unit pres sure between the bearing and the pressure member, andeliminates the necessity of aligning the various rollers very exactly;moreover, the forces transmitted through the parts follow a short path,since the distance between the plane AA and the first supporting bearing24 is slight.

If it is noted at the same time that all the various members throughwhich the forces are transmitted are preferably constructed of ferrousmetals, and that the equalization of the temperatures of the variousmembers is easily obtained since moving oil bathes them all, it will beseen that the variations in temperature cannot involve variations in thepressure of the bearing 28 on the pressure members. Since the bearing 28is amply dimensioned, its wear is practically negligible and itspressure on the pressure members does not vary.

Moreover, it will be noted that the distance between the support 7 andthe spring 20 is short. Since all the members of the pump are assumed tobe made of ferrous metals, this distance cannot vary much as a functionof the temperature so that the precision of the regulation of the spring20 is retained. 0n the other hand, the distance between the support 7and the diaphragm 39 is fairly great. Expansions of the stem 22 cantherefore displace slightly the diaphragm 39 and the support for thespring 51; but this is of no importance because the spring 51 is veryhighly flexible and the corresponding change of eifort will benegligible.

The device which has just been described is intended to be used for afour cylinder engine; it is naturally possible, without going outsidethe scope of the invention, to provide similar devices for enginescomprising any number of cylinders, the number of pressure membersvarying accordingly.

I claim:

A volumetric diaphragm pump comprising a flexible wall, a plurality ofpressure members lying in a plane and resting against the wall about theaxis of the pump, and means for actuating said pressure members in succession to effect delivery of fluid, said last-named means comprising asingle bearing roller rotatable about an axis which is oblique withrespect to said axis of the pump and forms an acute angle with saidlast-named axis with said two axes intersecting in said plane of thepressure members, and a support carrying said bearing roller androtatable about said axis of the pump, said bearing roller having atapered surface engageable with said pressure members which lies on thesurface of a cone having an axis coinciding with the axis of saidbearing roller, the cone having an obtuse apex angle at the intersectionof said axes and said bearing roller being mounted in said support forrotation about its axis to bring it into selective contact with saidpressure 1 members, a lifting support for the pressure 'membersto varythe delivery of the pumpja first extension of 'said'support passingthrough the flexible well against Which'th'e pressure members rest and.a regulating'spri n'g biased against said extension, and

'a secor'id 'extensiomoppos ite said first extension, a diaphragmconnected to'the end of said second extension, and a second springbiasing said extension in the direction ofsaid regulating springfsaiddiaphragm defining two chambers one of which is adapted to communicatewith the atmosphere and'the other with a source of different pneumaticpressure.

References Cited in the file of this patent UNITED STATES PATENTSDieckmann Oct. 25, 1898 Wahlmark Apr. 28, 1942 Vincent June 15, 1943Beeh Dec. 18, 1945 Wallace Apr. 13, 1948 Maillot Nov. 8, 1955 ChandlerMar. 6, 1956 FOREIGN PATENTS Great Britain Feb. 23, 1853

